Crescimento e desenvolvimento do algodoeiro BRS verde irrigado com águas salinas.

Abstract

The present study was carried out under greenhouse conditions at the EMBRAPA Cotton in the municipality of Campina Grande - PB, during the period of May to October 2003. The objective of the work was to study the growth, development and productivity of the green cotton BRS 200 irrigated with water of different salinity leveis. Problem that grows annually due to the inadequate management of the irrigation water in the exploration of socioeconomically important crop for the semi-arid. The treatments consisted of two types of water with varying proportions of Na:Ca (9.5:0.5 e 6.0:4.0), and six leveis of electrical conductivity of the irrigation water - (ECw- 2.0, 3.5, 5.0, 6.5, 8.0 and 9.5 dS m"1). The experimental design used was a completely radomized design in a 6 x 2 factorial scheme, resulted in 12 treatments with three repetitions, constituting of 36 factorial experientais. The variables such as number of days for germination, germination percentage and index of emergence speed were obtained up to 12 days after the seeding. The growth indexes: leaf number, plant height, stem diameter and leaf area, were appraised up to 120 days after seeding, being appraised at the same time the ratio of leaf area and index of root/aerial parts as well as dry weight of the aerial parts. The absolute and relative growth rates were obtained for the 30 and 90 days after the seeding. The salinity of the irrigation water did not affect the percentage of germination (GP) and index of germination speed. However, the increase in the salinity of the irrigation water reduced the vegetative growth significantly (number of leaves, plant height, stem diameter, leaf area, dry weight of the aerial parts). The germination of cotton was influenced by the salinity of the irrigation water, however a GP of 76.66% was obtained in the highest levei. The increase of ECw influenced significantly the leaf number, plant height, stem diameter, leaf area ratio and the dry weight of aerial part as the components of production - the number of capsule and mean weight of capsules. In case of mean weight of capsule, it increased of up to 4.41 dS m"1, reducing there after, 21.37% in the highest levei (9.5 dS m" '). It was also observed that the type of water did not influence any of the appraised variables.